I understand social skills questions, as I can be pretty awkward. You feel caught in a no-win situation because as you point out, you could be judged for either looking at them or not looking at them.

I was in a store once with a service animal I had at the time. A father was there with his little daughter. I cheerfully said to my dog, as I always did when we'd meet a small child, "Look, a *human* puppy." I referred to all small children as "human puppies" when talking to my dog. I have cats now, and small children are "human kittens" to them. I meant no harm. But the father gave me SUCH a glare. It didn't occur to me until afterward that the little girl had a disability. He must have thought I was putting her in the same category with my dog. Oh my gosh, I didn't mean it like that at all.

So those things happen. We will be misunderstood and judged for things we didn't intend. But I'd still say, treat a person with a disability the same as you'd treat anyone else. If you'd smile and make small talk with someone who doesn't have a visible disability, do the same for someone who does.

Oh, about rushing in to help... Unless someone is in immediate danger, I think it's a good idea to ask first. "Would you like me to get the door?" "Would you like help carrying that?" Then go by what they say.